C language islower() function: determine whether a character is a lowercase English letter

Function name : islower

Header file : <ctype.h>

Function prototype : int islower(int ch);

Function : Determine whether the character is a lowercase English letter

Parameters : int ch character to be checked

Return value : If ch is not a lowercase English letter, return 0. If ch is a lowercase English letter, return non-0.

Program example: Determine whether the entered characters are lowercase English letters

 #include<ctype.h>#include<stdio.h>intmain(){charch;printf(inputacharacter:);scanf(%c,&ch);if(islower(ch)){printf(%cisloweralpha.,ch) ;}else{printf(%cisnotloweralpha.,ch);}putchar('n');return0;}

Running results:

 inputacharacter:ggisloweralpha.